JPH0218012A - Contact lens and manufacture thereof - Google Patents

Abstract

PURPOSE: To reduce internal stress and to produce a lens having a complete optical lens surface and furthermore to reduce polishing work at processing by solidifying lens material in a mold cup and sticking it to the mold cup in the meantime and forming composite blank-mold cup structure. CONSTITUTION: A mold assembly 10 consists of a mold cup 11 and a molding die 13. A monomer mixture is polymerized in the inside of the mold cup 11 and contact-bonding phenomena are caused between polymerized lens material forming a lens blank 15 and the internal surface 14 of a recessed face 12. The die 13 has a low surface 16 with a projected shape. When the die 13 is separated from the lens blank 15, a true optical surface 17 is formed on the lens blank 15 in the interface of the polymerized material 15 and the surface 16 of the die 13. The blank 15 is formed of polymerizable lens material of thermoplastic or thermosetting material such as cellulose acetate butyrate and polymethyl methacrylate in the inside of the die formed of material contact-bonded to lens material. The lens material is tightly contact-bonded to the mold cup for shipment.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to novel means and methods for manufacturing contact lenses.

More particularly, the present invention relates to a novel method and means for casting contact lens blanks. That is, the lens material is molded into a cup (
It is then placed slowly into a mold cup, allowed to harden faithfully, and then shipped to manufacturers who produce lenses for contact lens operators (ophthalmologists and opticians).

BACKGROUND OF THE INVENTION Lenses for optical applications made of plastic materials are known. The primary purpose of such lenses is for contact lenses. Generally, contact lenses are
It can be roughly divided into two. One is what is usually characterized as a soft hydrophilic contact lens,
The other type is characterized as a rigid, gas-permeable hard contact lens, which is usually non-hydrophilic.

In addition to being classified as soft or hard, contact lenses are often classified as corneal or scleral. A corneal lens is a contact lens whose main attachment point is on the cornea of the eye. Another special type of lens is an intraocular lens that is surgically placed into the eye.

Due to the stringent requirements for first-class quality contact lenses, extreme precision is required in the fabrication of these lenses. Most plastic contact lens blanks begin by casting a long cylindrical rod of plastic material (eg, cellulose acetate butyrate, silicone acrylate, fluorosilicone acrylate, polymethyl methacrylate, etc.). This cylindrical rod is then cut transversely into several cylindrical lens blanks or buttons. These blanks, typically with opposing flat surfaces, are then sent to a lens fabricator where they are processed according to the prescription and then sent to an equipment supplier for application to a patient.

Various mechanical processes are performed on the blank. For example, it is common to machine the blank using a lathe equipped with a diamond bit or other processing tool (eg, a circular rotary tool bit). However, this mechanical operation creates specks on the lens surface, which are relevant to optical performance, and must be carefully polished to remove the specks. Insufficient polishing will leave lathe grooves on the optical surface, and excessive polishing will result in orange peel, resulting in a low-quality optical surface.

Another problem in making lenses from long rods is that it is difficult to process such rods with uniform density. Non-uniform density rods cause considerable optical problems, such as variations in the refractive index and also in the mechanical strength of the fabricated lenses.

In an effort to avoid some of the inherent problems of making plastic contact lens blanks from cut pieces of plastic rod, the prior art has developed a method for placing plastic between two parallel, spaced glass sheets.
It suggests a method of forming contact lenses in which a plastic sheet with a clear surface is formed between them.

This plastic sheet is then cut into quadrilaterals slightly larger than the desired diameter of the circular lens blank.

This quadrilateral is placed between spindles and rotated to cut the periphery to the desired diameter (the method is described in U.S. Pat. No. 3,651,192). Made of high quality plastic. Attempts have also been made to cast lenses. For example, U.S. Patent No. 3,380,
No. 718 suggests the use of a low concave mold filled with allyl diglycol carbonate. The concave shape is
It is lowered into the material by a centering rod mechanism. Heat until the solution becomes gel-like. In the gel state, additional pressure is applied to reduce shrinkage and other undesirable properties. Although this method has seen advances in the state of the art, it is still limited to - specific lenses for boat fishing, such as bifocal lenses.

And it cannot be applied to contact lenses or the various plastic materials typically used to make contact lenses. Distortion and shrinkage often occur with this method.

Another attempt at improving the method of casting contact lenses was by Neefe, U.S. Patent No. 4.457.
．． No. 880. That is, a lens blank with a finished optical surface is cast from a liquid monomer under an upper mold with an optical surface made from a resinous material that adheres to the upper surface of the polymeric lens material. Although this approach provides a handle while the resulting lens blank is being mechanically manipulated, it does not contribute in any way to reducing internal stresses on the lens or to providing transportation, and the resulting lens blank If the lens blank falls from the handle during machine operation, there is a risk of damage or loss, and conversely, the lens blank must be forcibly separated from the mold to which it is attached.The fatal point of Neefe's method is that the lens blank is attached to the mold cup. This means that it is completely non-adhesive.

In addition to the deficiencies of the prior art as described above, a series of other disadvantages of the prior art include the extreme abrasiveness of lens blanks made for hard gas permeability and soft lenses; This is due to the negative side effects that these blanks have on the lifespan of the diamond tools used to process them into usable lenses. Accordingly, yet another unmet need in the optical industry requires the development of means and methods for substantially reducing the degree of machining required to polish lens materials according to current practices. This is the aim of the present invention.
The aim is to reduce several of these deficiencies in the prior art.

SUMMARY OF THE INVENTION The present invention is directed to a novel method for molding optical lens blanks into mold cups that are specially formulated and designed so that the optical lens materials adhere strongly when solidified. be.

This method is particularly applicable for the production of soft or other everyday, ie long-wearing contact lenses, intraocular lenses and other optical lenses. The lens material solidifies in the mold cup, during which time it adheres to the cup and becomes "
A composite blank-shaped cup structure, referred to as a "lens button" is formed, which is sent as a unit to the lens manufacturer where the lens button is processed accordingly and subsequently placed on the patient. Completed as contact lenses to be handed over. As will be seen, the means and method of the present invention solves a major industrial problem and substantially extends the life of the diamond tools used therein. Further, as described below, the method of the present invention has substantially less internal stress than conventional methods.
Furthermore, a lens with a perfect optical lens surface is produced. Furthermore, the method of the present invention produces substantially fewer rejects than the prior art and is generally easier to manage, thus allowing for overall economical lens production.

It is therefore a primary object of the present invention to produce a composite cup which, when processed, can substantially reduce the abrasive action and thus prolong the useful life of the diamond tool used to form and complete the final contact lens. The object of the present invention is to provide a new and improved method of manufacturing contact lenses.

Another object of the present invention is to provide new means and methods for manufacturing contact lenses with substantially less internal stress and better optical surfaces than conventional methods.

Another object of the present invention is to provide a new means and method for manufacturing contact lens buttons in the form of a new shippable mold cup button which can be easily converted into contact lenses.

Yet another object of the present invention is to provide a new means and method for producing contact lenses having more uniformity and constant dimensional stability than in known methods.

BRIEF DESCRIPTION OF THE DRAWINGS Further objects of the invention will become clear from the following description and embodiments, particularly when taken in conjunction with the accompanying drawings.

(Preferred Embodiment) The present invention relates to a novel means and method for producing an optical lens using a molding technique, and the obtained lens has a convex surface, a concave surface or a flat surface depending on the purpose. When the lens is completed, the curved surface becomes the front or back surface of the finished lens, thus substantially reducing finishing operations. Furthermore, the invention can be used in the production of contact lenses of the erythematous, scleral, dicurved, aspheric, toric, spherical and biconvex types, as well as intraocular lenses, photographic lenses and magnifying lenses. I can do it.

To explain the attached drawings, especially FIGS. 1 and 2,
Mold assembly of the present invention (mold assen+bl
y) is shown at 10 and includes a mold cup 11 (with a concave surface 12 for the lens blank formed therein) and a mold die 13 (which covers the cover cup 11 and forms the part of the cup 11). placed on top;
Therein is a suitable monomer mixture prepared and introduced into the recess 12).

As the monomer mixture polymerizes in the cup 11, an adhesion phenomenon occurs between the polymerized lens material solidifying to form the lens blank 15 and the inner surface 14 of the concave surface 12, as shown in FIGS. 1 and 2. The die 13 has a convex lower surface 16 so that when the die 13 is separated from the polymeric lens material, i.e. the lens blank 15, it rests on the lens blank 15 at the interface of the polymeric material 15 and the surface 16 of the die 13. forming a true optical surface 17.

Each lens blank 15 is placed into a special mold cup 11, which will be described below. The blank 15 is placed in a mold made of a material calculated to adhere to the lens material.
For example, the lens material can be formed from suitable polymerizable lens materials such as thermoplastic and thermoset materials such as cellulose acetate butyrate, polymethyl methacrylate, silicone acrylate, fluorosilicone acrylate, etc. When sufficiently polymerized,
The lens material is firmly adhered to a mold cup for subsequent shipment. Details will be described later.

As mentioned above, the present invention is applicable to scleral, bicurved, intraocular, spherical, aspherical, toric, and
It can be widely applied to all types of optical lenses such as biconvex lenses and contact lenses. The means and methods here are 2.
- From common soft hydrophilic materials such as crosspolymers of hydroxyethylene methacrylate and ethylene glycol monomethacrylate or N-vinyl-2-pyrrolidone to cellulose acetate butyrate, silicone acrylate, fluorosilicone acrylate, polymethyl methacrylate, etc. Lenses made from a wide range of plastic materials, thermosets and thermoplastics, ranging from gas permeable or rigid materials approved for use such as mixtures of thermosets and thermoplastics.

In practice, the mold cup 11 is made of polymerizable lens material 1
It can be made from a variety of plastic materials that adhere to 4. Suitable materials for manufacturing molded cup 11 include, for example: That is, polyetherimide, polyamide, nylon, polycarbonate, acrylonitrile, polysulfone, PMMA, ethylene terephthalate, polybutylene terephthalate,
poly(methylpentene) as well as blended materials,
For example, acrylate styrene acrylonitrile (AS
A) and polycarbonate) (PC) Acrylonitrile butadiene styrene (ABS) and nylon, ABS and P
C, ABS and polytetrafluoroethylene (PTFE)
, ABS and polysulfone, ABS and polyvinyl chloride (PVC), ABS and styrene methacrylate (PMMA), ASA and PVC, acetal and PTFE
, PVC and acrylic, nylon and ethylene copolymer, nylon and polyethylene (PE), nylon and PT
FE, PC and PE, PC and polyethylene terephthalate (PET), PC and SMA, PC and polyurethane (T
PU), polybutylene terephthalate (PBT) and PE
T, PBT and elastomer PET and elastomer, PET
and polysulfone, polyphenylene ether (PPE) and polystyrene (PS), PPE and polyamide, polyphenylene sulfide (PPS) and PTFESPS
and elastomer, styrene acrylonitrile (SAN)
and ethylene propylene diene (EPDM), and SM
A and ps etc.

In practice, the particular polymer used as the cup material is
It depends on the particular monomer mixture chosen for the lens material.

The die 13 can be made of, for example, polypropylene, low and high density polyethylene, Teflon (registered trademark), phenol formaldehyde polymer, urea formaldehyde, poly(
They can be made from a wide variety of plastic materials that do not adhere to polymeric lens materials such as chlorotrifluoroethylene (chlorotrifluoroethylene), etc.

The mold cup 11 and die 13 are made by injection molding and necessary processing.

Preferably, the mold cup 11 is made of one of the materials mentioned above which solidifies into a relatively soft material which completely adheres to the monomer present in the recess 12 when the monomer is fully polymerized.

The mold cup 11 is shaped to form a spherical lens blank surface by shaping the lower surface 14 of the concave surface 12 as a curve, as shown in FIG. 3, or as shown in FIG. By shaping it as a flat surface, it is made to fit the contour in such a way as to form a flat lens blank surface.

The method of the invention is also suitable for making particularly large lenses in a mold cup 11 modified to have a larger cylindrical step in the cylindrical part 18, which steps are shown in FIGS. 5A and 5B. As shown, the recess 12 and the center are overlapped.

Suitably, the adhesion between the lens blank 15 and the mold cup 11 is defined by a plurality of generally concentric grooves 19 on the surface 14, as shown in FIGS. 6A and 6B, or as shown in FIGS. 7B, mechanical enhancement is achieved by providing a plurality of generally parallel axially extending splines 20 on the inner periphery 21 of the concave surface 12. In any of these, the groove 19 and the spline 20
increases the area of opposing surfaces between lens blank 15 and mold cup 11, thus increasing the desired adhesion therebetween.

Regardless of which of the several mold cups 11 described above is selected, the methodology used is essentially the same as follows.

Now, first select the mold cup 11 and place it on the level surface. Second, a polymerizable lens material mixture known to impart desired properties to the lens blank being formed is applied into a recess 12 that extends completely over the surface 14 so that the recess 12 is suitable. Inject until it is full. The die 13 is then placed thereon with the surface 16 with the lens material and the support surface 22 of the die 13 or cup 11 on the upper ring. Die 13 and mold cup 11 then work together to contain and shape the mixed monomers while they polymerize into a lens blank.

Curing is usually carried out at a temperature of at least 30°C or up to 100°C.
This is enhanced by heating for at least 30 minutes and up to 24 hours (depending on the monomer chosen for the lens material).

A specific initiator is incorporated therein and a uniform heating source is used, such as an oven, radiator, ultraviolet lamp, etc. Once the polymer is sufficiently cured, the heat source is removed, the die 13 is separated from the lens blank 15 and removed from the mold cup 11, and the resulting blank and mold cup composite units or buttons 23 are collected as needed for shipping. . The blank and mold cup unit 23 is essentially the same size as exposed lens blanks shipped according to the prior art.

This has even greater advantages, as discussed below.

In a contact lens manufacturing facility, contact lenses are manufactured from a unit of a blank and a mold cup as shown in FIGS. 3 and 4. That is, as shown, first, a portion of the mold cup 11 formed of a relatively soft material that can be quickly and easily machined with little or no wear on a polishing tool is inserted into the lens blank 15. Process the button 23 until it is exposed. This lens blank 15 is
Furthermore, the unnecessary part is cut away to manufacture a lens consisting only of the top part of the lens blank 15, and so on.
Make contact lenses usable.

The various parameters, processes and materials described here can be used to scale up the means and methods described here to produce large optical lenses, such as those used in cameras, telescopes and similar optical machines. It can be used for.

[Brief explanation of the drawing]

Figure IA is an exploded isometric view of a curved die cover and mold cup used to practice the present invention. Figure IB is an isometric view of a mold assembly for practicing the invention. FIG. 2 is a cross-sectional view of the mold assembly of FIG. IB along the line 1--2. FIG. 3 is a cross-sectional view of a curved blank and mold cup button unit with a curved interface between a mold cup and a lens blank according to the present invention, taken along line 1--H in FIG. IB. FIG. 4 is a cross-sectional view of a curved blank and mold cup button unit with a planar interface between the mold cup and the lens blank according to the present invention, taken along the line 1--2 in FIG. IB. FIG. 5A is a cross-sectional view along line ■-■ of FIG. 2 of another mold cup used in the application of the present invention and having a double-stepped mold cup periphery for the production of oversized lenses. It is. FIG. 5B is a planar front view of the mold cup of FIG. 5A. FIG. 6A shows the lines of FIG.
It is a sectional view taken along -■. FIG. 6B is a planar front view of the mold cup of FIG. 6A. FIG. 7A shows a slightly modified version of FIG. 2 of a cup of the present invention in which the axially extending splines are arranged in spaced, generally parallel relationship with each other about the approximate interior periphery of the recess. It is a sectional view along the line ■-■. FIG. 7B is a planar front view of the mold cup of FIG. 7A.

Claims (1)

[Claims] 1. A recess provided for receiving the monomer that is the uncured lens material, and a die support overlapping and circumscribing the recess and adapted to receive thereon a die cooperating therewith. a mold cup comprising a surface adapted to retain the monomer in the coating recess while the monomer is cured; a die with a curvature, which can be located on a supporting surface and can be removed therefrom to give a composite lens blank-type cup unit, suitable for finishing optical lenses. A mold assembly for manufacturing a composite lens blank-mold cup unit. 2. The mold assembly of clause 1, wherein the die has a curved lower surface that cooperates with a polymeric lens material formed thereon and adapted to form a curved optical surface. 3. The die contains polynytylene, polypropylene, phenol, formaldehyde polymer, urea formaldehyde, poly(chlorotrifluoroethylene) and Teflon (
2. The mold assembly of claim 2, wherein the mold assembly is formed of a non-adhesive material selected from the group consisting of: 4. The mold assembly of clause 1, wherein the mold cup has a cylindrical body circumscribing and enclosing the recess. 5. The mold assembly of clause 4, wherein the recess has a lower surface that supports the lens material monomers before and during curing and firmly adheres to the fully cured lens material. 6. The mold assembly of clause 5, wherein the lower surface is planar. 7. The mold assembly of clause 5, wherein the lower surface is a curved surface. 8. The mold assembly of clause 5, wherein the lower surface has a plurality of spaced concentric grooves clearly defined therein. 9. The mold assembly of clause 5, wherein the recess has a plurality of spaced axially extending splines clearly defined around its interior periphery. 10. The mold cup is made of polyetherimide, polyamide, nylon, polycarbonate, acrylonitrile, polysulfone, PMMA, ethylene tetraphthalate, polymethylbentene, as well as blend materials such as acrylate styrene acrylonitrile (ASA) and polycarbonate (PC) acrylonitrile butadiene styrene. (ABC) and nylon, ABS and PC, ABS and polytetrafluoroethylene (PTFE), ABS and polysulfone, ABS and polyvinyl chloride (PVC), AB
S and styrene methacrylate (PMMA), ASA and P
VC, acetal and PTFE, PVC and acrylic,
Nylon and ethylene copolymer, nylon and polyethylene (PE), nylon and PTFE, PC and PE, PC and polyethylene terephthalate (PET), PC and SMA
, PC and polyurethane (TPU), polybutylene terephthalate (PBT) and PET, PBT and elastomer,
PET and elastomer, PET and polysulfone, polyphenylene ether (PPE) and polystyrene (PS),
PPE and polyamide, polyphenylene sulfide (P
PS) and PTFE, PS and elastomer, styrene acrylonitrile (SAN) and ethylene propylene diene (
The mold assembly according to claim 1, comprising a monomer or monomer mixture selected from the group consisting of EPDM), SMA and PS, etc. 11. The mold of clause 10, wherein the die has a curved lower surface formed thereon, which cooperates with polymeric lens material thereon to form a curved optical lens surface. assembly. 12. Clause 11, wherein the die is formed from a non-adhesive material selected from the group consisting of polyethylene, polypropylene, phenol, formaldehyde polymer, urea formaldehyde, poly(chlorofluoroethylene), and Teflon. mold assembly. 13. The mold assembly of clause 10, wherein the mold cup has a cylindrical body circumscribing and enclosing the recess. 14. The mold assembly of clause 13, wherein the recess has a low surface for supporting the lens material monomer before or during its curing and for firmly adhering to the fully cured lens material. 15. The mold assembly of clause 14, wherein the lower surface is planar. 16. The mold assembly of clause 14, wherein the lower surface is spherical. 17. The mold assembly of clause 14, wherein the lower surface has a plurality of spaced concentric grooves therein. 18. The mold assembly of clause 14, wherein the recess has a plurality of spaced axially extending splines on its interior surface. 19, polyetherimide, polyamide, nylon, polycarbonate, acrylonitrile, polysulfone, P
MMA, ethylene terephthalate, polybutylene terephthalate, poly(methylpentene), as well as blended materials such as acrylatestyrene acrylonitrile (ASA) and polycarbonate (PC) acrylonitrile butadiene styrene (ABS) and nylon, ABS
and PC, ABS and polytetrafluoroethylene (PTF)
E), ABS and polysulfone, ABS and polyvinyl chloride (PVC), ABS and styrene methacrylate (
PMMA), ASA and PVC, acetal and PTFE,
PVC and acrylic, nylon and ethylene copolymer, nylon and polyethylene (PE), nylon and PTF
E, PC and PE, PC and polyethylene terephthalate (
PET), PC and SMA, PC and polyurethane (TPU
), polybutylene terephthalate (PBT) and PET, PBT and elastomer, PET and elastomer, PET and polysulfone, polyphenylene ether (PPE) and polythretin (PS), PPE and polyamide, polyphenylene sulfite (PPS) and PTFE, PS and elastomer , styrene acrylonitrile (SAN) and ethylene propylene diene (EPDM)
), and a mold cup having a concave portion is made from a plastic material selected from the group consisting of SMA, PS, etc., an uncured lens monomer material mixture is placed in the concave portion, and a die cover with a curvature is placed on the mold cup. heating the monomer in the mold cup until the monomer is cured into adhesive relationship with the mold cup to form a composite lens blank-mold cup unit;
and removing a curved die therefrom to create an optical surface on the cured monomer. 20. providing an optical surface on a mold die comprised of a material that does not adhere to the polymerized lens material when polymerized and solidifies; providing a mold cup comprising a material that adheres to the polymerized lens material during polymerization; Filling the mold cup with a polymerizable lens material, covering the lens cup and the polymerizable lens material with the mold die, and processing the filled mold assembly to fill the mold cup with the polymerizable lens material. a polymerization process comprising the steps of: polymerizing to a polymerized solid that adheres to the cup but not to the mold die; and removing the mold die from the mold assembly to obtain a lens blank-mold cup unit assembly. A method of casting a lens blank having an optical finish on at least one surface of a suitable lens material. 21. Processing the unit assembly to remove the mold cup, further processing the polymeric solid lens material to remove all attached lens material, and finishing the remainder of the solid lens material into a contact lens. 21. The method of manufacturing a lens from a lens blank cup assembly according to claim 20. 22. A final optical lens manufactured by the method of item 19. 23. The final optical lens of item 22, wherein the lens is a contact lens. 24. Manufacture a lens blank-mold cup unit according to the method of paragraph 19, process the lens blank-mold cup unit to remove the mold cup and all external lens material, and use the remaining solid lens material to form a known formulation. 1. A method for fitting a contact lens to a patient with a known prescription, characterized by finishing a final contact lens that meets the requirements of the patient, and fitting the completed contact lens to a patient who has the prescription.